Everything but...
First off, I'd like to say it works. The red lights are a great indicator of whether or not the controller is plugged in, most of the buttons are mapped respectively. This is where I come to my problems with the adapter. We are down 3 buttons. 2 due to the GameCube controller's design and 1 from the adaptors design. Now losing the select and one of the z buttons isn't a complete loss, but you really appreciate the start button once it's been removed. On the switch, it's now registered as the Home button. I get what they were going for, but now I can't get past the opening cutscene to Blaster Master Zero. On paper, it makes sense to make the start button a home button. However, the start button is very much in a large number of games.
Now it does work with other games on switch fine if you don't need the 3 missing buttons. I think what it's best for is experimenting on other USB compatable devices. There's bound to be creative ways to us the adaptor, but on the switch it feels hindered and that's just because of one button.
If you want to use a GameCube controller on a USB compatable device this is so far the best priced item I've seen on the market.
What I would recommend to make it better? Well I find the Turbo Button unnecessary so if that can be removed in place of a home button that would make the placement all the more fitting. If there is a way to have an extra z and add a select button through the adapter I welcome it, but I'll take the home button idea if Brook will consider it.
